Mauna Kea: how to have a safe and enjoyable visit

Protect your heart

If you have a heart condition, do not ascend the mountain without
checking with your physician. Your heart's arterial vessels dilate
with prolonged exposure to the high altitude. This increases the
flow of blood to the cardiac muscle, so you should carefully monitor
your physical activity and pulse rate, and remember to pace yourself.
Even light exertion at a high altitude may increase your pulse rate
to more than 100. This will put more demand on your heart. Altitude
medicine can help this problem, but if you have cardiac artery disease,
too much exertion could lead to a cardiac incident.

Effect on respiration

Your respiratory rate will also increase. This may cause hyperventilation,
which results in light-headedness and a general body tingling sensation.

Protect yourself from ultraviolet radiation

At high altitudes, there is less of an atmosphere to filter out
the harmful ultraviolet rays that cause sunburn. You may receive
first-degree and even second-degree burns after only 15 minutes
of unprotected exposure. Given time--five minutes per day for about
one week--your skin can make enough ultraviolet-absorbing pigment
to protect itself. As a precaution, wear sunscreen during the daytime,
and watch out for white patches on your nose and ears. Practice
the buddy system--watch out for others. To protect your eyes from
ultraviolet rays, wear dark glasses during the daytime.

Other effects on your eyes

You may experience eye pain, decreased tolerance to light, and
decreased night vision.

Don't smoke

If you smoke, abstain from smoking for at least 48 hours before
your ascent to allow the amount of carbon monoxide in your blood
to decrease. The blood supply to your lungs will then increase,
as will your breathing capacity, unless your lungs have been damaged
by tobacco.

Drink plenty of water

Drink plenty of water prior to your ascent both to provide your
kidneys with enough fluid to work properly and to avoid dehydration
from pulmonary water losses. Your kidneys will dump their excess
water and sodium to concentrate your blood, hastening your adaptation
to low oxygen levels.

Avoid gas-producing foods

Foods such as beans, onions, and cabbage may cause intestinal gas
to expand, resulting in flatulence, bowel distension, and even pain
at high altitudes.

Headaches and impaired mental abilities

At high altitudes, your blood vessels dilate to increase the flow
of oxygen-carrying blood to the brain. This may cause a pounding
headache. Medication prescribed by a physician may partially compensate
for this, but you should still be alert for other effects of decreased
oxygen: impaired decision-making, memory, and mathematical ability.

Do not Scuba dive before ascent

Breathing at sea-level pressures allows nitrogen gas in your bloodstream
to dissipate readily by exhalation; this process is greatly reduced
at high altitudes, so you should not scuba dive for 24 hours prior
to ascending the mountain. If you SCUBA dive below 50 feet within
12 hours of ascent, you risk formation of nitrogen bubbles in your
joints and brain, a dangerous condition known as "the bends."
You should not ascend the mountain for at least 48 hours after you
have dived below 100 feet.